1. Field of the Invention
This invention relates generally to freight vehicles and more particularly to freight vehicles having a cargo space which is capable of handling bulk goods, including bulk liquid product, as well as being capable of handling piece goods, such as boxed or palletized goods.
2. Prior Art
Freight vehicles which can handle either piece goods or bulk goods are generally known. The advantage of such convertibility is that the same cargo space on the same vehicle could handle either of these two significantly different types of loads. The term "piece goods" is defined herein to mean any goods which are handled as individual items or pieces, including packaged goods or palletized goods. The term "bulk goods" means any goods which are pourable and commonly shipped in bulk, such as powder, grain, flake, fluid or liquid materials. The term "freight vehicle"encompasses any vehicle capable of containing freight or cargo, including without limitation tractor-trailers, railway cars, ships, aircraft, domestic and I.S.O. containers, and intermodal freight vehicles.
For example, U.S. Pat. No. 4,534,596, issued Aug. 13, 1985, incorporated in its entirety by reference herein, discloses a freight vehicle having a conventional cargo space for piece goods, wherein the cargo space includes openings in the roof and floor for filling and discharging bulk material. Specially constructed bulk material container bags are deployed from the roof under the inlet openings and extend to the floor over the outlet openings. The bags are filled with bulk material through the inlet openings in the roof, and when the vehicle has arrived at the shipment destination the material is discharged from the outlet openings in the floor. To allow handling of piece goods, the bags are retractable to a stored and locked position on the ceiling of the cargo space.
Freight vehicles also are known which are capable of handling bulk liquid product. In addition to conventional tank trucks, it is known to provide conventional tractor-trailer vehicles with elongated collapsible liquid cargo bags which are adapted to be filled with liquid product. While such liquid cargo bags are secured to the cargo space of the vehicle using various securing means such as harness straps, a major problem in the transportation of bulk liquid product has been the sloshing motion of the bulk liquid during transportation. Such sloshing motion can make the vehicle difficult to control, potentially causing an accident, and additionally, can cause a vehicle to jack-knife or tip over.
The sloshing motion is caused by the kinetic energy that is generated when a large mass traveling at a given speed in a given direction is subjected to a rapid change in speed caused by acceleration or deceleration, or a sudden change in direction caused by the making of a turn. This energy when imparted to the liquid mass can build up over time as the vehicle continues on its route, potentially causing the problems discussed above. There thus exists a need in the art for improvement in systems using such bulk liquid cargo bags in convertible freight transportation vehicles.